U.S. patent number 8,530,605 [Application Number 13/320,484] was granted by the patent office on 2013-09-10 for poly(arylene sulfide) and production process thereof.
This patent grant is currently assigned to Kureha Corporation. The grantee listed for this patent is Akihiro Konno, Hiroshi Sakabe, Ken-ichi Takaki. Invention is credited to Akihiro Konno, Hiroshi Sakabe, Ken-ichi Takaki.
United States Patent |
8,530,605 |
Konno , et al. |
September 10, 2013 |
Poly(arylene sulfide) and production process thereof
Abstract
The invention provides a production process of a poly(arylene
sulfide), comprising a polymerization step of subjecting at least
one sulfur source selected from the group consisting of alkali
metal sulfides and alkali metal hydrosulfides and a dihalo-aromatic
compound to a polymerization reaction in an organic amide solvent;
a reaction step of adding a hydroxyl group-containing organic
compound containing no bonded halogen atom in a proportion of 0.001
to 20 mol per 100 mol of the charged sulfur source into the
polymerization reaction system containing the organic amide solvent
and a formed polymer after the polymerization step to cause the
formed polymer to react with the hydroxyl group-containing organic
compound; and a collecting step of collecting a polymer from the
polymerization reaction system after the reaction step, and the
poly(arylene sulfide).
Inventors: |
Konno; Akihiro (Tokyo,
JP), Sakabe; Hiroshi (Tokyo, JP), Takaki;
Ken-ichi (Tokyo, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Konno; Akihiro
Sakabe; Hiroshi
Takaki; Ken-ichi |
Tokyo
Tokyo
Tokyo |
N/A
N/A
N/A |
JP
JP
JP |
|
|
Assignee: |
Kureha Corporation (Tokyo,
JP)
|
Family
ID: |
43126126 |
Appl.
No.: |
13/320,484 |
Filed: |
May 11, 2010 |
PCT
Filed: |
May 11, 2010 |
PCT No.: |
PCT/JP2010/057931 |
371(c)(1),(2),(4) Date: |
November 14, 2011 |
PCT
Pub. No.: |
WO2010/134445 |
PCT
Pub. Date: |
November 25, 2010 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20120065361 A1 |
Mar 15, 2012 |
|
Foreign Application Priority Data
|
|
|
|
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May 18, 2009 [JP] |
|
|
2009-119841 |
|
Current U.S.
Class: |
528/196;
528/198 |
Current CPC
Class: |
C08G
75/0213 (20130101); C08G 75/0254 (20130101); C08G
75/0268 (20130101); C08G 75/029 (20130101); C08G
75/0259 (20130101); C08G 75/0272 (20130101) |
Current International
Class: |
C08G
64/00 (20060101); C08G 63/02 (20060101) |
Field of
Search: |
;528/381,388 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
62-106929 |
|
May 1987 |
|
JP |
|
62-184026 |
|
Aug 1987 |
|
JP |
|
63-33775 |
|
Jul 1988 |
|
JP |
|
2-209925 |
|
Aug 1990 |
|
JP |
|
5-163349 |
|
Jun 1993 |
|
JP |
|
2000-191785 |
|
Jul 2000 |
|
JP |
|
2004/060972 |
|
Jul 2004 |
|
WO |
|
2010/010760 |
|
Jan 2010 |
|
WO |
|
Primary Examiner: Boykin; Terressa
Attorney, Agent or Firm: Porter Wright Morris & Arthur
LLP
Claims
The invention claimed is:
1. A production process of a poly(arylene sulfide), comprising the
following steps: (1) a polymerization step of subjecting at least
one sulfur source selected from the group consisting of alkali
metal sulfides and alkali metal hydrosulfides and a dihalo-aromatic
compound to a polymerization reaction in an organic amide solvent;
(2) a reaction step of adding a hydroxyl group-containing organic
compound containing no bonded halogen atom in a proportion of 0.001
to 20 mol per 100 mol of the charged sulfur source into the
polymerization reaction system containing the organic amide solvent
and a polymer formed in the polymerization step after the
polymerization step to cause the formed polymer to react with the
hydroxyl group-containing organic compound; and (3) a collecting
step of collecting a polymer formed in the reaction step from the
polymerization reaction system containing the formed polymer after
the reaction step.
2. The production process according to claim 1, wherein the
polymerization step comprises a phase-separation polymerization
step of continuing the polymerization reaction in the presence of a
phase separation agent in a phase-separated state that a
concentrated formed polymer phase and a dilute formed polymer phase
are present in a mixed state within the polymerization reaction
system after the polymerization reaction of at least one sulfur
source selected from the group consisting of alkali metal sulfides
and alkali metal hydrosulfides with the dihalo-aromatic compound is
initiated, and wherein the reaction step is a step of adding the
hydroxyl group-containing organic compound into the polymerization
reaction system lying in the phase-separated state after the
phase-separation polymerization step to cause the formed polymer to
react with the hydroxyl group-containing organic compound while
retaining the phase-separated state.
3. The production process according to claim 1, wherein the
polymerization step comprises: i) a first-stage polymerization step
of subjecting at least one sulfur source selected from the group
consisting of alkali metal sulfides and alkali metal hydrosulfides
and the dihalo-aromatic compound to a polymerization reaction in
the organic amide solvent to form a polymer that a conversion of
the dihalo-aromatic compound is 80 to 99%; and ii) a second-stage
polymerization step of continuing the polymerization reaction in
the presence of a phase separation agent in a phase-separated state
that a concentrated formed polymer phase and a dilute formed
polymer phase are present in a mixed state within the
polymerization reaction system, and wherein the reaction step is a
step of adding the hydroxyl group-containing organic compound into
the polymerization reaction system lying in the phase-separated
state after the second-stage polymerization step to cause the
formed polymer to react with the hydroxyl group-containing organic
compound while retaining the phase-separated state.
4. The production process according to claim 1, wherein the
polymerization step comprises: I) a first-stage polymerization step
of subjecting at least one sulfur source selected from the group
consisting of alkali metal sulfides and alkali metal hydrosulfides
and the dihalo-aromatic compound to a polymerization reaction at a
temperature of 170 to 270.degree. C. in the organic amide solvent
in a state that water is present in a proportion of 0.02 to 2.0 mol
per mol of the charged sulfur source, thereby forming a polymer
that a conversion of the dihalo-aromatic compound is 80 to 99%; and
II) a second-stage polymerization step of controlling the amount of
water in the polymerization reaction system so as to bring about a
state that water exists in a proportion of from higher than 2.0 mol
to not higher than 10 mol per mol of the charged sulfur source, and
heating the polymerization reaction system to a temperature of 245
to 290.degree. C., thereby continuing the polymerization reaction
in a phase-separated state that a concentrated formed polymer phase
and a dilute formed polymer phase are present in a mixed state
within the polymerization reaction system, and wherein the reaction
step is a step of adding the hydroxyl group-containing organic
compound into the polymerization reaction system lying in the
phase-separated state after the second-stage polymerization step to
cause the formed polymer to react with the hydroxyl
group-containing organic compound while retaining the
phase-separated state.
5. The production process according to claim 1, wherein prior to
the polymerization step, are arranged 1) a dehydration step of
heating a mixture containing the organic amide solvent, a sulfur
source containing an alkali metal hydrosulfide, and an alkali metal
hydroxide in a proportion of 0.95 to 1.05 mol per mol of the alkali
metal hydrosulfide to discharge at least a part of a distillate
containing water from the interior of the system containing the
mixture to the exterior of the system; and 2) a charging step of
adding an alkali metal hydroxide and water to the mixture remaining
in the system after the dehydration step, as needed, to adjust the
mixture in such a manner that the total number of moles of the
number of moles of an alkali metal hydroxide formed with hydrogen
sulfide formed upon the dehydration, the number of moles of the
alkali metal hydroxide added prior to the dehydration and the
number of moles of the alkali metal hydroxide added after the
dehydration step becomes 1.00 to 1.09 mol per mol of a charged
sulfur source existing in the system after the dehydration step,
and the number of moles of water becomes 0.02 to 2.0 mol per mol of
the charged sulfur source, wherein the polymerization step
comprises: 3) a first-stage polymerization step of adding the
dihalo-aromatic compound to the mixture to subject the sulfur
source and the dihalo-aromatic compound to a polymerization
reaction at a temperature of 170 to 270.degree. C. in the organic
amide solvent, thereby forming a polymer that a conversion of the
dihalo-aromatic compound is 80 to 99%; and 4) a second-stage
polymerization step of controlling the amount of water in the
polymerization reaction system so as to bring about a state that
water exists in a proportion of from higher than 2.0 mol to not
higher than 10 mol per mol of the charged sulfur source, and
heating the polymerization reaction system to a temperature of 245
to 290.degree. C., thereby continuing the polymerization reaction
in a phase-separated state that a concentrated formed polymer phase
and a dilute formed polymer phase are present in a mixed state
within the polymerization reaction system; and wherein the reaction
step is a step of adding the hydroxyl group-containing organic
compound into the polymerization reaction system lying in the
phase-separated state after the second-stage polymerization step to
cause the formed polymer to react with the hydroxyl
group-containing organic compound while retaining the
phase-separated state.
6. The production process according to claim 1, wherein in the
polymerization step, the dihalo-aromatic compound is caused to
react in an amount of from more than 1.00 mol to not more than 1.09
mol per mol of the charged sulfur source.
7. The production process according to claim 1, wherein in the
reaction step, the hydroxyl group-containing organic compound is
added into the polymerization reaction system containing the
organic amide solvent and the polymer formed in the polymerization
step after the polymerization step, and the formed polymer is then
reacted with the hydroxyl group-containing organic compound under
conditions of a temperature ranging from 170 to 290.degree. C. and
a reaction time ranging from 5 minutes to 3 hours.
8. The production process according to claim 1, wherein in the
collecting step, a poly(arylene sulfide) having a melt viscosity of
1 to 100 Pas as measured at a temperature of 310.degree. C. and a
shear rate of 1,216 sec.sup.-1, a weight-average molecular weight
of 10,000 to 60,000 as measured by gel permeation chromatography,
an average particle diameter of 100 to 1,000 .mu.m as measured by a
sifting method and a bonded halogen atom content of lower than
4,000 ppm as measured by the flask combustion method is
collected.
9. The production process according to claim 1, wherein the
hydroxyl group-containing organic compound is at least one hydroxyl
group-containing organic compound selected from the group
consisting of aliphatic alcohols, alicyclic alcohols, aromatic
alcohols and phenolic compounds.
10. The production process according to claim 1, wherein the
hydroxyl group-containing organic compound is a hydroxyl
group-containing organic compound having a boiling point of
100.degree. C. or higher and containing one hydroxyl group.
11. The production process according to claim 1, wherein the
hydroxyl group-containing organic compound is at least one aromatic
alcohol selected from the group consisting of benzyl alcohol,
o-tolylmethanol, m-tolylmethanol, p-tolylmethanol,
p-isopropylbenzyl alcohol, 1-phenylethanol, 2-phenylethanol,
1-phenyl-1-propanol, 1-phenyl-2-propanol and
3-phenyl-1-propanol.
12. The production process according to claim 1, wherein the
hydroxyl group-containing organic compound is at least one phenolic
compound selected from the group consisting of phenol, cresol,
ethylphenol, p-t-butylphenol, p-t-pentylphenol, xylenol,
2,6-di-t-butyl-p-cresol, pentamethylphenol and phenoxyphenol.
13. A poly(arylene sulfide) obtained by subjecting at least one
sulfur source selected from the group consisting of alkali metal
sulfides and alkali metal hydrosulfides and a dihalo-aromatic
compound to a polymerization reaction in an organic amide solvent,
wherein (a) the poly(arylene sulfide) is a reaction product with a
hydroxyl group-containing organic compound containing no bonded
halogen atom, and at least part of bonded halogen atoms thereof
have been removed by a reaction with the hydroxyl group-containing
organic compound, (b) the melt viscosity thereof is 1 to 100 Pas as
measured at a temperature of 310.degree. C. and a shear rate of
1,216 sec.sup.-1, (c) the weight-average molecular weight thereof
is 10,000 to 60,000 as measured by gel permeation chromatography,
(d) the average particle diameter thereof is 100 to 1,000 .mu.m as
measured by a sifting method, and (e) the content of bonded halogen
atoms thereof is lower than 4,000 ppm as measured by the flask
combustion method.
14. The poly(arylene sulfide) according to claim 13, wherein the
content of bonded halogen atoms is 3,900 ppm or lower.
15. The poly(arylene sulfide) according to claim 13, wherein the
content of bonded halogen atoms is 2,000 ppm or lower.
Description
TECHNICAL FIELD
The present invention relates to a production process of a
poly(arylene sulfide) containing halogen atom(s) (may referred to
as "terminal halogen group(s)") bonded to terminal(s) of its
polymer chain, the content of the bonded halogen atom(s) in said
poly(arylene sulfide) having been reduced. More particularly, the
present invention relates to a production process of a poly(arylene
sulfide) by subjecting at least one sulfur source selected from the
group consisting of alkali metal sulfides and alkali metal
hydrosulfides and a dihalo-aromatic compound to a polymerization
reaction in an organic amide solvent, by which the content of the
bonded halogen atom(s) can be efficiently reduced by a reaction
treatment with a hydroxyl group-containing organic compound at a
final-stage of a polymerization step.
The present invention also relates to a poly(arylene sulfide)
obtained by subjecting at least one sulfur source selected from the
group consisting of alkali metal sulfides and alkali metal
hydrosulfides and a dihalo-aromatic compound to a polymerization
reaction in an organic amide, wherein at least part of bonded
halogen atom(s) in said poly(arylene sulfide) has been removed by a
reaction with a hydroxyl group-containing organic compound.
BACKGROUND ART
Poly(arylene sulfides) (hereinafter abbreviated as "PASs")
represented by poly(phenylene sulfide) (hereinafter abbreviated as
"PPS") are engineering plastics excellent in heat resistance,
chemical resistance, flame retardancy, mechanical strength,
electrical properties, dimensional stability, etc. The PASs are
commonly used in a wide variety of technical fields such as
electrical equipments, electronic equipments, automotive equipments
and packaging materials because they can be molded or formed into
various kinds of molded or formed products, films, sheets, fibers,
etc. by general melt processing processes such as extrusion,
injection molding and compression molding.
As a typical production process of a PAS, is known a process in
which a sulfur source is reacted with a dihalo-aromatic compound in
an organic amide solvent such as N-methyl-2-pyrrolidone. As the
sulfur source, is generally used an alkali metal sulfide, an alkali
metal hydrosulfide or a mixture thereof. When the alkali metal
hydrosulfide is used as the sulfur source, the alkali metal
hydrosulfide is used in combination with an alkali metal
hydroxide.
When at least one sulfur source selected from the group consisting
of alkali metal sulfides and alkali metal hydrosulfides is
subjected to a polymerization reaction with a dihalo-aromatic
compound, a great amount of an alkali metal salt such as NaCl is
secondarily produced by a desalting polycondensation reaction. The
alkali metal salt remaining in the resulting PAS adversely affects
the electrical properties of the PAS because the salt is an
electrolyte. When the PAS containing the remaining alkali metal
salt is applied to a sealing compound or covering material for
electronic parts, the alkali metal salt corrodes electrodes and
wirings of the electronic parts, causes disconnection or makes a
leakage current great.
The problems caused by the alkali metal salt remaining in the PAS
have come to be almost overcome at present. A technique for foaming
a high-molecular weight granular PAS in a polymerization step is
established as disclosed in, for example, Japanese Patent
Publication No. 63-33775 (Patent Literature 1). The granular PAS is
easy to be sifted by a screen, and impurities such as alkali metal
salts and oligomers can be easily removed from the granular PAS by
washing. With respect to a purification method of a PAS collected
after polymerization also, is adopted an effective washing method
by combining, for example, water washing, washing with an organic
solvent, acid washing, etc. In fact, the PAS sufficiently washed is
purified to the extent that ash derived from the remaining alkali
metal salt such as NaCl is substantially not obtained even when it
is burnt. As described above, according to the present state of the
art, a PAS substantially containing no remaining alkali metal salt
can be obtained.
However, it is difficult even by the present state of the art to
reduce the content of halogen atom(s) bonded mainly to terminal(s)
of a polymer chain of a PAS. When a sulfur source and a
dihalo-aromatic compound are subjected to a polymerization
reaction, a PAS with halogen atom(s) bound to one terminal or both
terminals thereof is formed. This bonded halogen atom cannot be
removed by washing. The sulfur source and the dihalo-aromatic
compound are reacted in equimolar amounts to form a polymer. In
order to stably perform the polymerization reaction, however, it is
desirable to adjust a charged molar ration of the dihalo-aromatic
compound to the sulfur source in such a manner that the molar
ration of the dihalo-aromatic compound to the sulfur source becomes
somewhat excessive. On the other hand, if the molar ration of the
dihalo-aromatic compound to the sulfur source becomes too
excessive, a PAS with halogen atoms bonded to both terminals of its
polymer chain is liable to be formed.
The requirement of halogen-free regulation on the whole polymer
product from environmental groups is heightened in addition to the
requirement of halogen content reduction in PASs by electronic part
makers from the viewpoint of the performance of electronic parts,
and PAS makers bear the responsibility of satisfying these
requirements. In order to reduce the halogen content in a PAS, it
is essential to reduce the content of the bonded halogen atoms in
addition to the reduction of the remaining alkali metal salt.
As a method for reducing the content of the bonded halogen atoms in
the PAS, Japanese Patent Application Laid-Open No. 62-106929
(Patent Literature 2) proposes a method of subjecting
poly(phenylene sulfide) (PPS) and a mercapto group-containing
compound or a salt thereof to a heat treatment in a solvent capable
of dissolving the poly(phenylene sulfide). The method disclosed in
Patent Literature 2 includes a step of collecting, washing and
drying the PPS after sodium sulfide and p-dichlorobenzene are
polymerized in N-methyl-2-pyrrolidone. Patent Literature 2 shows an
experimental example that the PPS dried, the mercapto
group-containing compound or the salt thereof and the solvent were
charged into an autoclave to react them under heating. Patent
Literature 2 describes that the contents were poured into water
after completion of the reaction under heating, washing with hot
water and filtration were conducted repeatedly, washing with
methanol was then conducted, and vacuum drying was conducted to
isolate a polymer.
According to the method described in Patent Literature 2, PPS whose
content of a bonded chlorine has been greatly reduced can be
obtained. However, the method of Patent Literature 2 is not
efficient because the PPS must be caused to further react with the
particular reaction reagent at a high temperature over a long
period of time in the solvent after the PPS is collected from the
polymerization reaction system and purified after polymerization,
and a purification step including filtering, washing and drying is
required after the reaction. In short, the method described in
Patent Literature 2 is complicated in operation and moreover also
low in energy efficiency.
Japanese Patent Application Laid-Open No. 5-163349 (Patent
Literature 3) proposes a process for producing a PAS having a low
bonded chlorine content by subjecting a cyclic arylene sulfide
oligomer to ring-opening polymerization under heating in the
presence of a ring-opening polymerization catalyst. However, the
process disclosed in Patent Literature 3 requires to extract a 7-
to 15-mer cyclic phenylene sulfide oligomer from a PPS formed after
a polymerization reaction of sodium sulfide with p-dichlorobenzene
in an organic amide solvent by Soxhlet extraction using methylene
chloride as a solvent. Therefore, the process of Patent Literature
3 is not a process suitable for production of the PAS on an
industrial scale.
Citation List
Patent Literature
Patent Literature 1: Japanese Patent Publication No. 63-33775
(corresponding to U.S. Pat. No. 4,645,826) Patent Literature 2:
Japanese Patent Application Laid-Open No. 62-106929 (corresponding
to U.S. Pat. No. 4,820,801) Patent Literature 3: Japanese Patent
Application Laid-Open No. 5-163349 (corresponding to U.S. Pat. No.
5,384,391)
SUMMARY OF INVENTION
Technical Problem
It is an object of the present invention to provide a production
process capable of obtaining a poly(arylene sulfide) whose content
of bonded halogen atoms including terminal halogen groups has been
reduced by a relatively simple and efficient method capable of
being incorporated into a polymerization step.
The present inventors have carried out an extensive investigation
with a view toward achieving the above object. As a result, it has
been found that after a polymerization step of subjecting at least
one sulfur source selected from the group consisting of alkali
metal sulfides and alkali metal hydrosulfides and a dihalo-aromatic
compound to a polymerization reaction in an organic amide solvent,
a hydroxyl group-containing organic compound containing no bonded
halogen atom is added into the polymerization reaction system
containing the organic amide solvent and a polymer formed to cause
the formed polymer to react with the hydroxyl group-containing
organic compound, thereby obtaining a poly(arylene sulfide) whose
content of bonded halogen atoms has been reduced.
According to the production process of the present invention, the
reaction of the formed polymer with the hydroxyl group-containing
organic compound can be incorporated into the polymerization step,
so that it is only necessary to conduct a step of collecting the
PAS once from the reaction mixture to purify it. In other words,
according to the production process of the present invention, it is
not necessary to dissolve the PAS collected from the polymerization
reaction system and purified in the solvent under heating and cause
it to react with the reagent. Therefore, according to the
production process of the present invention, it is not necessary to
conduct the step of collecting the PAS twice from the reaction
mixture to purify it repeatedly as disclosed in the method
described in Patent Literature 2. According to the production
process of the present invention, the hydroxyl group-containing
organic compound can be introduced under pressure into the
polymerization reaction system lying in a high-temperature state
after the polymerization step and caused to react, so that the
energy efficiency is high.
When a phase-separation polymerization step that the polymerization
reaction is continued in the presence of a phase separation agent
in a phase-separated state that a concentrated formed polymer phase
and a dilute formed polymer phase are present in a mixed state
within the polymerization reaction system after the polymerization
reaction of the sulfur source with the dihalo-aromatic compound in
the organic amide solvent is initiated is arranged in the
production process of the present invention, a granular PAS having
average particle diameter of generally at least 100 .mu.m,
preferably at least 200 .mu.m can be obtained. Such a granular PAS
is easy to be sifted by a screen and high in removal efficiency of
the remaining alkali metal salt and oligomers by washing.
According to the production process of the present invention, the
content of the bonded halogen atoms, melt viscosity, weight-average
molecular weight, average particle diameter, etc. of the resulting
PAS can be optionally adjusted by, for example, controlling the
polymerization reaction conditions and selecting the kind of the
hydroxyl group-containing organic compound. Therefore, according to
the production process of the present invention, the various
properties of the PAS can be controlled as necessary for the end
application intended. The PAS obtained according to the production
process of the present invention can be provided as a product
having a halogen content suitable for use as a sealing compound for
electronic parts by diluting it with a large amount of a filler
even when the bonded halogen atom content thereof is not very low.
The present invention has been led to completion on the basis of
these findings.
Solution to Problem
According to the present invention, there is provided a production
process of a poly(arylene sulfide), comprising the following steps:
(1) a polymerization step of subjecting at least one sulfur source
selected from the group consisting of alkali metal sulfides and
alkali metal hydrosulfides and a dihalo-aromatic compound to a
polymerization reaction in an organic amide solvent; (2) a reaction
step of adding a hydroxyl group-containing organic compound
containing no bonded halogen atom in a proportion of 0.001 to 20
mol per 100 mol of the charged sulfur source into the
polymerization reaction system containing the organic amide solvent
and a polymer formed in the polymerization step after the
polymerization step to cause the formed polymer to react with the
hydroxyl group-containing organic compound; and (3) a collecting
step of collecting a polymer formed in the reaction step from the
polymerization reaction system containing the formed polymer after
the reaction step.
According to the present invention, there is also provided a
poly(arylene sulfide) obtained by subjecting at least one sulfur
source selected from the group consisting of alkali metal sulfides
and alkali metal hydrosulfides and a dihalo-aromatic compound to a
polymerization reaction in an organic amide solvent, wherein (a)
the poly(arylene sulfide) is a reaction product with a hydroxyl
group-containing organic compound containing no bonded halogen
atom, and at least part of bonded halogen atoms thereof have been
removed by a reaction with the hydroxyl group-containing organic
compound, (b) the melt viscosity thereof is 1 to 100 Pas as
measured at a temperature of 310.degree. C. and a shear rate of
1,216 sec.sup.-1, (c) the weight-average molecular weight thereof
is 10,000 to 60,000 as measured by gel permeation chromatography,
(d) the average particle diameter thereof is 100 to 1,000 .mu.m as
measured by a sifting method, and (e) the content of bonded halogen
atoms thereof is lower than 4,000 ppm as measured by the flask
combustion method.
Advantageous Effects of Invention
According to the production process of the present invention, a
poly(arylene sulfide) whose content of bonded halogen atoms
including terminal halogen groups has been reduced by a relatively
simple and efficient method capable of being incorporated into a
polymerization step can be obtained. The PAS obtained by the
production process according to the present invention can meet the
requirements of halogen content reduction from various fields and
can be suitably utilized in a wide variety of fields such as
electrical and electronic equipments and automotive equipments,
including sealing compounds or covering materials for electronic
parts.
DESCRIPTION OF EMBODIMENTS
1. Sulfur Source
In the present invention, at least one sulfur source selected from
the group consisting of alkali metal sulfides and alkali metal
hydrosulfides is used as a sulfur source. As examples of the alkali
metal sulfides, may be mentioned lithium sulfide, sodium sulfide,
potassium sulfide, rubidium sulfide, cesium sulfide and mixtures of
two or more compounds thereof. As examples of the alkali metal
hydrosulfides, may be mentioned lithium hydrosulfide, sodium
hydrosulfide, potassium hydrosulfide, rubidium hydro sulfide,
cesium hydrosulfide and mixtures of two or more compounds
thereof.
The alkali metal sulfide may be used in any form of an anhydride, a
hydrate and an aqueous solution. Among these, sodium sulfide and
lithium sulfide are preferred in that they are industrially
available on the cheap. The alkali metal sulfide is preferably used
as an aqueous mixture (i.e., a mixture with water having fluidity)
such as an aqueous solution from the viewpoints of processing
operation, metering, etc.
The alkali metal hydrosulfide may be used in any form of an
anhydride, a hydrate and an aqueous solution. Among these, sodium
hydrosulfide and lithium hydrosulfide are preferred in that they
are industrially available on the cheap. The alkali metal
hydrosulfide is preferably used as an aqueous solution or an
aqueous mixture (i.e., a mixture with water having fluidity) from
the viewpoints of processing operation, metering, etc.
In general, a small amount of an alkali metal hydrosulfide is
secondarily produced in a production process of the alkali metal
sulfide. A small amount of the alkali metal hydrosulfide may be
contained in the alkali metal sulfide used in the present
invention. In this case, the total molar quantity of the alkali
metal sulfide and alkali metal hydrosulfide becomes a charged
sulfur source after a dehydration step.
On the other hand, in general, a small amount of an alkali metal
sulfide is secondarily produced in a production process of the
alkali metal hydrosulfide. A small amount of the alkali metal
sulfide may be contained in the alkali metal hydrosulfide used in
the present invention. In this case, the total molar quantity of
the alkali metal hydrosulfide and alkali metal sulfide becomes a
charged sulfur source after a dehydration step. When the alkali
metal sulfide and the alkali metal hydrosulfide are mixed and used
in combination, a mixture of both naturally becomes a charged
sulfur source.
When the sulfur source contains the alkali metal hydrosulfide, an
alkali metal hydroxide is used in combination. Examples of the
alkali metal hydroxide include lithium hydroxide, sodium hydroxide,
potassium hydroxide, rubidium hydroxide, cesium hydroxide and
mixtures of two or more compounds thereof. Among these, sodium
hydroxide and lithium hydroxide are preferred in that they are
industrially available on the cheap. The alkali metal hydroxide is
preferably used as an aqueous solution or aqueous mixture.
In the production process according to the present invention,
examples of water to be dehydrated in the dehydration step includes
water of hydration, a water medium of an aqueous solution and water
secondarily produced in a reaction of the alkali metal hydrosulfide
with the alkali metal hydroxide.
2. Dihalo-Aromatic Compound
The dihalo-aromatic compound used in the present invention is a
dihalogenated aromatic compound having 2 halogen atoms directly
bonded to a aromatic ring. Specific examples of the dihalo-aromatic
compound include o-dihalobenzenes, m-dihalobenzenes,
p-dihalobenzenes, dihalotoluenes, dihalonaphthalenes,
methoxy-dihalobenzenes, dihalobiphenyls, dihalobenzoic acids,
dihalodiphenyl ethers, dihalodiphenyl sulfones, dihalodiphenyl
sulfoxides and dihalodiphenyl ketones. Among these,
p-dihalobenzenes, m-dihalobenzenes and mixtures of these both
compounds are preferred, and p-dihalobenzenes are more
preferred.
The halogen atom means each atom of fluorine, chlorine, bromine and
iodine, and 2 halogen atoms in the same dihalo-aromatic compound
may be the same or different from each other. These dihalo-aromatic
compounds may be used either singly or in any combination
thereof
The charged amount of the dihalo-aromatic compound is generally
0.90 to 1.50 mol, preferably 1.00 to 1.10 mol, more preferably 1.00
to 1.09 mol, particularly preferably more than 1.00 mol, but not
more than 1.09 mol per mol of the sulfur source (alkali metal
sulfide and/or alkali metal hydrosulfide) remaining in the system
after a dehydration step. When the charged amount of the
dihalo-aromatic compound falls within the range of 1.01 to 1.09
mol, good results can be yielded in many cases. If a molar ratio of
the dihalo-aromatic compound charged to the sulfur source is too
high, it is difficult to form a high-molecular weight polymer. If a
molar ratio of the dihalo-aromatic compound charged to the sulfur
source is too low on the other hand, a decomposition reaction is
easy to occur, and it is difficult to stably perform a
polymerization reaction. However, when the molar ratio of the
dihalo-aromatic compound is made high, the content of terminal
halogen groups generally becomes high.
3. Branching or Crosslinking Agent
In order to introduce a branched or crosslinked structure into a
formed PAS, a polyhalo-compound (may not be always an aromatic
compound), to which at least 3 halogen atoms are bonded, an active
hydrogen-containing halogenated aromatic compound, a halogenated
aromatic nitro compound or the like may also be used in
combination. Preferable examples of the polyhalo-compound as a
branching or crosslinking agent include trihalobenzenes.
4. Organic Amide Solvent
In the present invention, an organic amide solvent that is an
aprotic polar organic solvent is used as a solvent for a
dehydration reaction and a polymerization reaction. The organic
amide solvent is preferably stable to an alkali at a high
temperature. Specific examples of the organic amide solvent include
amide compounds such as N,N-dimethylformamide and
N,N-dimethylacetamide; N-alkylcaprolactam compounds such as
N-methyl-.epsilon.-caprolactam; N-alkylpyrrolidone compounds or
N-cycloalkylpyrrolidone compounds such as N-methyl-2-pyrrolidone
and N-cyclohexyl-2-pyrrolidone; N,N-dialkylimidazolidinone
compounds such as 1,3-dialkyl-2-imidazolidinones; tetraalkylurea
compounds such as tetramethylurea; and hexaalkylphosphoric triamide
compounds such as hexamethylphosphoric triamide. These organic
amide solvents may be used either singly or in any combination
thereof.
Among these organic amide solvents, N-alkyl-pyrrolidone compounds,
N-cycloalkylpyrrolidone compounds, N-alkylcaprolactam compounds and
N,N-dialkylimilazolidinone compounds are preferred, and
N-methyl-2-pyrrolidone, N-methyl-.epsilon.-caprolactam and
1,3-dialkyl-2-imidazolidinones are particularly preferably used.
The amount of the organic amide solvent used in the polymerization
reaction in the present invention is generally within a range of
0.1 to 10 kg per mol of the sulfur source.
5. Polymerization Aid
In the present invention, various kinds of polymerization aids may
be used as needed for promoting the polymerization reaction.
Specific examples of the polymerization aids include water, organic
carboxylic acid metal salts, organic sulfonic acid metal salts,
alkali metal halides such as lithium halides, alkaline earth metal
halides, aromatic carboxylic acid alkaline earth metal salts,
phosphoric acid alkali metal salts, alcohols, paraffinic
hydrocarbons and mixtures of 2 or more compounds thereof, which are
generally publicly known as polymerization aids for PASs. Alkali
metal carboxylates are preferred as the organic carboxylic acid
metal salts. As examples of the alkali metal carboxylates, may be
mentioned lithium acetate, sodium acetate, potassium acetate,
sodium propionate, lithium valerate, lithium benzoate, sodium
benzoate, sodium phenylacetate, potassium p-toluylate and mixtures
of 2 or more compounds thereof. Sodium acetate is particularly
preferred as the alkali metal carboxylate because it is cheap and
easy to be available. The amount of the polymerization aid used
varies according to the kind of the compound used. However, it is
within a range of generally 0.01 to 10 mol, preferably 0.1 to 2
mol, more preferably 0.2 to 1.8 mol, particularly preferably 0.3 to
1.7 mol per mol of the charged sulfur source. When the
polymerization aid is an organic carboxylic acid metal salt,
organic sulfonic acid salt or alkali metal halide, it is desirable
that the upper limit of the used amount thereof is preferably at
most 1 mol, more preferably at most 0.8 mol per mol of the charged
sulfur source.
6. Phase Separation Agent
In order to promote the polymerization reaction to obtain a PAS
having a high polymerization degree in a short period of time,
various kinds of phase separation agents are preferably used in the
present invention. The phase separation agent is a compound that is
dissolved in the organic amide solvent and has a function of
lowering the solubility of the PAS in the organic amide solvent by
itself or under the coexistence of a small amount of water. The
phase separation agent itself is a compound that is not a solvent
for PASs.
As the phase separation agent, may be used a compound generally
known to function as a phase separation agent in the technical
field of PASs. The above-described compounds used as the
polymerization aid are also included in the phase separation agent.
In the present invention, however, the phase separation agent means
a compound used in an amount or proportion that can function as a
phase separation agent in the phase-separation polymerization step.
Specific examples of the phase separation agent include water,
organic carboxylic acid metal salts, organic sulfonic acid metal
salts, alkali metal halides such as lithium halides, alkaline earth
metal halides, aromatic carboxylic acid alkaline earth metal salts,
phosphoric acid alkali metal salts, alcohols and paraffinic
hydrocarbons. As the organic carboxylic acid metal salts, are
preferred alkali metal carboxylates such as, for example, lithium
acetate, sodium acetate, potassium acetate, sodium propionate,
lithium valerate, lithium benzoate, sodium benzoate, sodium
phenylacetate and potassium p-toluylate. These phase separation
agents may be used either singly or in any combination thereof.
Among these phase separation agents, water and alkali metal
carboxylates are preferred because they are cheap, and water is
particularly preferred. The amount of the phase separation agent
used varies with the kind of the compound used. However, it is
generally within a range of 0.01 to 10 mol per mol of the charged
sulfur source.
When the production process of the present invention includes a
phase-separation polymerization step, it is preferable to cause
water to exist as the phase separation agent in a proportion of
higher than 2.0 mol to not higher than 10 mol, preferably 2.2 to 7
mol, more preferably 2.5 to 5 mol per mol of the charged sulfur
source within the polymerization reaction system in the
phase-separation polymerization step. Another phase separation
agent such as the organic carboxylic acid metal salt than water is
used within a range of preferably 0.01 to 3 mol, more preferably
0.02 to 2 mol, particularly preferably 0.03 to 1 mol per mol of the
charged sulfur source.
Even when water is used as the phase separation agent, another
phase separation agent than water may be used as a polymerization
aid in combination from the view point of efficiently conducting
phase-separation polymerization. When water and another phase
separation agent are used in combination in the phase-separation
polymerization step, the total amount thereof may be an amount
sufficient to cause phase separation. In the phase-separation
polymerization step, water is caused to exist in a proportion of
higher than 2.0 mol to not higher than 10 mol, preferably 2.2 to 7
mol, more preferably 2.5 to 5 mol per mol of the charged sulfur
source within the polymerization reaction system, and another phase
separation agent may be used in combination within a range of
preferably 0.01 to 3 mol, more preferably 0.02 to 2 mol,
particularly preferably 0.03 to 1 mol. When water and another phase
separation agent are used in combination, water is used within a
range of 0.5 to 10 mol, preferably 0.6 to 7 mol, particularly
preferably 0.5 to 5 mol per mol of the charged sulfur source, and
another phase separation agent such as the alkali metal carboxylate
may also be used in combination within a range of 0.001 to 0.7 mol,
preferably 0.02 to 0.6 mol, particularly preferably 0.05 to 0.5 mol
in order to perform phase-separation polymerization with a small
amount of the phase separation agents.
7. Dehydration Step
A dehydration step is preferably arranged as a preliminary step for
a polymerization step to control the amount of water in the
reaction system. The dehydration step is performed by a process
comprising heating and reacting a mixture containing the organic
amide solvent and the alkali metal sulfide, desirably, under an
inert gas atmosphere and discharging water outside the system by
distillation. When the alkali metal hydrosulfide is used as a
sulfur source, the dehydration step is performed by a process
comprising heating and reacting a mixture containing the alkali
metal hydrosulfide and an alkali metal hydroxide and discharging
water outside the system by distillation.
In the dehydration step, the dehydration is conducted until the
content of water comprising water of hydration (water of
crystallization), a water medium, secondarily produced water, etc.
is lowered within a range of necessary amounts. In the dehydration
step, the dehydration is conducted until the content of water
coexisting in the polymerization reaction system is reduced to
generally 0.02 to 2.0 mol, preferably 0.05 to 2.0 mol, more
preferably 0.5 to 2.0 mol per mol of the charged sulfur source. The
sulfur source after the dehydration step is called "a charged
sulfur source". If the water content has become too low in the
dehydration step, water may be added prior to the polymerization
step to regulate the water content to a desired value.
When the alkali metal hydrosulfide is used as the sulfur source, a
mixture containing the organic amide solvent, the alkali metal
hydrosulfide and an alkali metal hydroxide in a proportion of 0.95
to 1.05 mol per mol of the alkali metal hydrosulfide is preferably
heated and reacted to discharge at least a part of a distillate
containing water from the interior of the system containing the
mixture to the exterior of the system in the dehydration step.
If a molar ratio of the alkali metal hydroxide to a mole of the
charged alkali metal hydrosulfide in the dehydration step is too
low, the amount of a sulfur component (hydrogen sulfide)
volatilized off in the dehydration step becomes great, which tends
to incur reduction in productivity due to lowering of the amount of
the charged sulfur source or cause abnormal reactions and
deterioration of quality of a PAS formed due to increase of a
polysulfide component in the charged sulfur source remaining after
the dehydration. If the molar ratio of the alkali metal hydroxide
to a mole of the charged alkali metal hydrosulfide is too high, in
some cases, change in properties of the organic amide solvent may
be increased, difficulty may be encountered on stably performing
the polymerization reaction, or the yield and quality of a PAS
formed may be deteriorated. A preferable molar ratio of the alkali
metal hydroxide to a mole of the charged alkali metal hydrosulfide
in the dehydration step is 0.97 to 1.04, more preferably 0.98 to
1.03.
In many cases, a small amount of an alkali metal sulfide is
contained in an alkali metal hydrosulfide, so that the amount of
the sulfur source involves a total of the alkali metal hydrosulfide
and the alkali metal sulfide. No problem arises as to a raw
material for the PAS even if the alkali metal hydrosulfide contains
the alkali metal sulfide. However, the content thereof is
preferably as low as possible for producing a high-quality PAS in
the present invention. Even when a small amount of the alkali metal
sulfide is mixed in, the molar ratio to the alkali metal hydroxide
may be calculated out on the basis of the content (analytical
value) of the alkali metal hydrosulfide in the present invention to
regulate the molar ratio between them.
The charging of the respective raw materials into a reaction vessel
in the dehydration step is conducted within a temperature range of
generally from ordinary temperature (5 to 35.degree. C.) to
300.degree. C., preferably from ordinary temperature to 200.degree.
C. The charging order of the raw materials may be optionally set,
and the respective raw materials may be additionally charged in the
course of the dehydration process. An organic amide solvent is used
as a solvent used in the dehydration step. This solvent is
preferably the same as the organic amide solvent used in the
polymerization step, and N-methyl-2-pyrrolidone is particularly
preferred. The amount of the organic amide solvent used is
generally of the order of 0.1 to 10 kg per mol of the sulfur source
charged in the reaction vessel.
The dehydration process is conducted by heating the mixture after
charging the raw materials into the reaction vessel in a
temperature range of generally up to 300.degree. C., preferably 100
to 250.degree. C. for generally 15 minutes to 24 hours, preferably
30 minutes to 10 hours. Heating methods include a method of
retaining a fixed temperature, a method of raising the temperature
either stepwise or continuously and a method of combining both
methods. The dehydration step is conducted by, for example, a batch
system, a continuous system or a combined system of both
systems.
An apparatus for conducting the dehydration step may be the same as
a reaction vessel (reactor) used in the subsequent polymerization
step or different from it. A material of the apparatus is
preferably a corrosion resistant material such as titanium. In the
dehydration step, a part of the organic amide solvent is generally
discharged together with water outside the reaction vessel. At that
time, hydrogen sulfide is discharged as a gas outside the
system.
8. Charging Step
In the present invention, an alkali metal hydroxide and/or water
may be added to the mixture remaining in the system after the
dehydration step as needed. When the alkali metal hydrosulfide is
used as the sulfur source in particular, the mixture is desirably
adjusted in such a manner that the total number of moles of the
number of moles of an alkali metal hydroxide formed with hydrogen
sulfide formed upon the dehydration, the number of moles of the
alkali metal hydroxide added prior to the dehydration and the
number of moles of the alkali metal hydroxide added after the
dehydration becomes preferably 1.00 to 1.09 mol, more preferably
more than 1.00 mol, but not more than 1.09 mol per mol of a charged
sulfur source including the alkali metal hydrosulfide existing in
the system after the dehydration as a sulfur source, and the number
of moles of water becomes generally 0.02 to 2.0 mol, preferably
0.05 to 2.0 mol, more preferably 0.5 to 2.0 mol per mol of the
charged sulfur source. The amount of the charged sulfur source is
calculated out in accordance with an equation, [Charged sulfur
source]=[Total moles of sulfur charged]-[Moles of sulfur
volatilized off after dehydration].
When hydrogen sulfide is volatilized off in the dehydration step,
an alkali metal hydroxide is produced by an equilibrium reaction
and comes to remain in the system. Accordingly, it is necessary to
exactly grasp the amount of hydrogen sulfide volatilized off to
determine a molar ratio of the alkali metal hydroxide to the sulfur
source in the charging step.
If the molar ratio of the alkali metal hydroxide to a mole of the
charged sulfur source is too high, it is liable to increase change
in properties of the organic amide solvent or cause abnormal
reactions or decomposition reactions upon polymerization. In
addition, the lowering of the yield and quality of a PAS formed is
often caused. The molar ratio of the alkali metal hydroxide to a
mole of the charged sulfur source is preferably 1.01 to 1.08 mol,
more preferably 1.015 to 1.075 mol. It is preferable to conduct the
polymerization reaction slightly in excess of the alkali metal
hydroxide in that the polymerization reaction is stably performed
to obtain a high-quality PAS.
In the present invention, the sulfur source in the charging step is
decided to be called "a charged sulfur source" for distinguishing
it from the sulfur source used in the dehydration step. The reason
for it is that the amount of the sulfur source poured into the
reaction vessel in the dehydration step is varied by the
dehydration step. The charged sulfur source is consumed by a
reaction with a dihalo-aromatic compound in the polymerization
step. However, the molar quantity of the charged sulfur source is
based on a molar quantity in the charging step.
9. Polymerization Step
The polymerization step is conducted by charging a dihalo-aromatic
compound into the mixture after completion of the dehydration step
and heating the sulfur source and the dihalo-aromatic compound in
the organic amide solvent. When a polymerization vessel different
from the reaction vessel used in the dehydration step is used, the
mixture after the dehydration step and the dihalo-aromatic compound
are charged into the polymerization vessel. After the dehydration
step and before the polymerization step, the amounts of the organic
amide solvent and coexisting water may be controlled as needed.
Before the polymerization step or during the polymerization step, a
polymerization aid and other additives may be mixed.
The mixing of the mixture obtained after completion of the
dehydration step with the dihalo-aromatic compound is conducted
within a temperature range of generally 100 to 350.degree. C.,
preferably 120 to 330.degree. C. When the respective components are
charged into the polymerization vessel, no particular limitation is
imposed on the order of charging, and the charging is conducted by
partially charging both components in small portions or charging
both components at a time.
In general, the polymerization reaction is preferably conducted by
a two-stage process of a first-stage polymerization step and a
second-stage polymerization step at a temperature ranging from 170
to 290.degree. C. As a heating method, is used a method of
retaining a fixed temperature, a method of raising the temperature
either stepwise or continuously or a combination of both methods.
The polymerization reaction time is within a range of generally
from 10 minutes to 72 hours, desirably from 30 minutes to 48
hours.
The amount of the organic amide solvent used in the polymerization
step is within a range of generally 0.1 to 10 kg, preferably 0.15
to 5 kg per mol of the charged sulfur source existing in the
polymerization step. The amount may be changed in the course of the
polymerization reaction so far as it falls within this range. The
content of the coexisting water upon the beginning of the
polymerization reaction is desirably controlled within a range of
generally 0.02 to 2.0 mol, preferably 0.05 to 2.0 mol, more
preferably 0.5 to 2.0 mol per mol of the charged sulfur source. It
is preferable to increase the content of the coexisting water in
the course of the polymerization reaction.
In the production process according to the present invention, the
polymerization reaction in the polymerization step is preferably
conducted through at least two-stage polymerization steps
comprising: i) a first-stage polymerization step of subjecting at
least one sulfur source selected from the group consisting of
alkali metal sulfides and alkali metal hydrosulfides and a
dihalo-aromatic compound to a polymerization reaction in an organic
amide solvent to form a polymer that a conversion of the
dihalo-aromatic compound is 80 to 99%; and ii) a second-stage
polymerization step of continuing the polymerization reaction in
the presence of a phase separation agent in a phase-separated state
that a concentrated formed polymer phase and a dilute formed
polymer phase are present in a mixed state within the
polymerization reaction system.
In the production process according to the present invention, the
polymerization reaction in the polymerization step is more
preferably conducted through at least two-stage polymerization
steps comprising: I) a first-stage polymerization step of
subjecting at least one sulfur source selected from the group
consisting of alkali metal sulfides and alkali metal hydrosulfides
and a dihalo-aromatic compound to a polymerization reaction at a
temperature of 170 to 270.degree. C. in an organic amide solvent in
a state that water is present in a proportion of 0.02 to 2.0 mol
per mol of a charged sulfur source, thereby forming a polymer that
a conversion of the dihalo-aromatic compound is 80 to 99%; and II)
a second-stage polymerization step of controlling the amount of
water in the polymerization reaction system so as to bring about a
state that water exists in a proportion of from higher than 2.0 mol
to not higher than 10 mol per mol of the charged sulfur source, and
heating the polymerization reaction system to a temperature of 245
to 290.degree. C., thereby continuing the polymerization reaction
in a phase-separated state that a concentrated formed polymer phase
and a dilute formed polymer phase are present in a mixed state
within the polymerization reaction system.
The amount of the coexisting water in the reaction system in the
first-stage polymerization step is within a range of generally 0.02
to 2.0 mol, preferably 0.05 to 2.0 mol, more preferably 0.5 to 2.0
mol, particularly preferably 1.0 to 1.9 mol per mol of the charged
sulfur source. The amount of the coexisting water in the
first-stage polymerization step may be small. However, undesirable
reactions such as decomposition of a PAS formed are easy to occur
if the amount of the coexisting water is too small. If the amount
of the coexisting water exceeds 2.0 mol, a polymerization rate
becomes markedly low, or decomposition of the organic amide solvent
and a PAS formed is easy to occur. Thus, such a too small or great
amount is not preferable. The polymerization is conducted within a
temperature range of 170 to 270.degree. C., preferably 180 to
265.degree. C. If the polymerization temperature is too low, the
polymerization rate becomes too slow. If the polymerization
temperature is a high temperature exceeding 270.degree. C. on the
other hand, decomposition of a PAS formed and the organic amide
solvent is easy to occur, and the polymerization degree of the PAS
formed becomes extremely low.
If the amount of the coexisting water in the reaction system in the
second-stage polymerization step is not more than 2.0 mol or more
than 10 mol per mol of the charged sulfur source, the
polymerization degree of a PAS formed is lowered. It is
particularly preferred to conduct the second-stage polymerization
in a state that the amount of the coexisting water falls within a
range of 2.2 to 7 mol because a PAS having a high polymerization
degree is easy to be obtained. If the polymerization temperature in
the second-stage polymerization step is lower than 245.degree. C.,
a PAS having a high polymerization degree is difficult to be
obtained. If the polymerization temperature exceeds 290.degree. C.,
there is a possibility that a PAS formed and the organic amide
solvent may be decomposed. In particular, a temperature range of
250 to 270.degree. C. is preferred because a PAS having a high
polymerization degree is easy to be obtained. The second-stage
polymerization step in the present invention is not the mere step
of fractionating and granulating a polymer (may referred to as "a
prepolymer") formed in the first-stage polymerization step, but a
step of increasing the polymerization degree of the polymer. Water
is preferably used as the phase separation agent in the
second-stage polymerization step. However, another phase separation
agent (polymerization aid; for example, an organic carboxylic acid
metal salt) may be used in place of water or together with water
within a range of preferably 0.01 to 3 mol per mol of the charged
sulfur source.
When the alkali metal hydrosulfide is used as the sulfur source,
the polymerization reaction in the polymerization step is
preferably conducted through at least two-stage polymerization
steps comprising: (1) a first-stage polymerization step of heating
a reaction mixture containing the organic amide solvent, the sulfur
source, the dihalo-aromatic compound and an alkali metal hydroxide
at a specific molar ratio to 170 to 270.degree. C. in the presence
of water in a proportion of generally 0.02 to 2.0 mol, preferably
0.05 to 2.0 mol, more preferably 0.5 to 2.0 mol per mol of the
charged sulfur source to conduct a polymerization reaction, thereby
forming a polymer that a conversion of the dihalo-aromatic compound
is 80 to 99%, and (2) a second-stage polymerization step of
controlling the amount of water in the polymerization reaction
system so as to bring about a state that water exists in a
proportion of from higher than 2.0 mol to not higher than 10 mol
per mol of the charged sulfur source, and heating the
polymerization reaction system to a temperature of 245 to
290.degree. C., thereby continuing the polymerization reaction.
Water is preferably used as the phase separation agent in the
second-stage polymerization step. However, another phase separation
agent (polymerization aid; for example, an organic carboxylic acid
metal salt) may be used in place of water or together with water
within a range of preferably 0.01 to 3 mol per mol of the charged
sulfur source.
In the first-stage polymerization step, it is desirable to form a
polymer (prepolymer) having a melt viscosity of generally 0.5 to 30
Pas as measured at a temperature of 310.degree. C. and a shear rate
of 1,216 sec.sup.-1.
Water may be added at a final stage of the polymerization reaction
or upon completion thereof to increase the water content for the
purpose of lowering the contents of a secondarily produced alkali
metal salt (for example, NaCl) and impurities in the polymer formed
or collecting the polymer in the form of granules. The system of
the polymerization reaction may be a batch system, a continuous
system or a combination of both systems. In the batch-wise
polymerization, 2 or more reaction vessels may be used, if desired,
for the purpose of shortening the polymerization cycle time.
The conversion of the dihalo-aromatic compound in the first-state
polymerization step is a value calculated out in accordance with
each of the following equations. When the dihalo-aromatic compound
(abbreviated as "DHA") is added in excess in terms of a molar ratio
to the sulfur source, the conversion is calculated out in
accordance with the following equation: Conversion=[(Charged amount
(mol) of DHA)-(Remaining amount (mol) of DHA)]/[(Charged amount
(mol) of DHA)-(Excessive amount (mol) of DHA)].times.100.
In other case, the conversion is calculated out in accordance with
the following equation: Conversion=[(Charged amount (mol) of
DHA)-(Remaining amount (mol) of DHA)]/[(Charged amount (mol) of
DHA)].times.100. 10. Reaction with Hydroxyl Group-Containing
Organic Compound
In the present invention, a reaction step of adding a hydroxyl
group-containing organic compound containing no bonded halogen atom
in a proportion of 0.01 to 20 mol per 100 mol of the charged sulfur
source into the polymerization reaction system containing the
organic amide solvent and the formed polymer to cause the formed
polymer to react with the hydroxyl group-containing organic
compound is arranged after such polymerization steps as described
above. A collecting step of acquiring the polymer from the
polymerization reaction system is arranged after this reaction
step.
As the hydroxyl group-containing organic compound, is used at least
one organic compound selected from the group consisting of
aliphatic alcohols, alicyclic alcohols, aromatic alcohols and
phenolic compounds which each do not contain a bonded halogen atom.
The hydroxyl group-containing organic compound is preferably an
organic compound having a boiling point of 100.degree. C. or higher
and containing one hydroxyl group.
Examples of the aliphatic alcohols include monohydric saturated
aliphatic alcohols such as methanol, ethanol, 1-propanol,
2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, 2-methyl-1
-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol,
3-methyl-1-butanol, 3-methyl-2-butanol, 2-methyl-2-butanol,
2,2-dimethyl-1-propanol, 1-hexanol, 2-hexanol, 3-hexanol,
2-methyl-1-pentanol, 2-methyl-2-pentanol, 4-methyl-1-pentanol,
4-methyl-2-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol,
3-methyl-3-pentanol, 2,3-dimethyl-1-butanol,
3,3-dimethyl-2-butanol, 1-heptanol, 2-heptanol, 3-heptanol,
4-heptanol, 3-ethyl-3-pentanol, 2,4-dimethyl-3-pentanol,
2,3,3-trimethyl-2-butanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol,
1-nonanol, 2-nonanol, 2,6-dimethyl-4-hepfanol, 1-decanol,
1-undecanol, 1-tridecanol, 1-tetradecanol, 1-pentadecanol,
1-hexadecanol, 1-heptadecaonol, 1-octadecanol, 1-hexacosanol,
1-triacontanol and 1-hentriacontanol; monohydric unsaturated
aliphatic alcohols such as allyl alcohol, trans-2-buten-1-ol and
3-buten-1-ol; dihydric alcohols such as ethylene glycol,
1,2-propanediol and 1,3-propanediol; and polyhydric alcohols such
as glycerol and pentaerythritol. These aliphatic alcohols may be
used either singly or in any combination thereof.
As examples of the alicyclic alcohols, may be mentioned monohydric
alicyclic alcohols such as cyclopentanol, cyclohexanol,
1-methylcyclohexanol, cis-2-methyl- cyclohexanol,
trans-2-methylcyclohexanol, cis-3-methyl-cyclohexanol,
trans-3-methylcyclohexanol, cis-4-methylcyclohexanol and
trans-4-methylcyclohexanol. These alicyclic alcohols may be used
either singly or in any combination thereof.
The aromatic alcohol is an alcohol having an aromatic ring, to
other carbon atom(s) than carbon atoms forming the aromatic ring of
which a hydroxyl group is bonded. As examples of the aromatic
alcohol, may be mentioned monohydric aromatic alcohols such as
benzyl alcohol, o-tolylmethanol, m-tolylmethanol, p-tolylmethanol,
p-isopropylbenzyl alcohol, 1-phenylethanol, 2-phenylethanol,
1-phenyl-1-propanol, 1-phenyl-2-propanol and 3-phenyl-1-propanol.
These aromatic alcohols may be used either singly or in any
combination thereof.
The phenolic compound is an alcohol, to a carbon atom of the
aromatic ring of which a hydroxyl group is bonded. As examples of
the phenolic compound, may be mentioned monohydric phenolic
compounds such as phenol, cresol, ethylphenol, p-t-butylphenol,
p-t-pentylphenol, xylenol, 2,6-di-t-butyl-p-cresol,
pentamethylphenol and phenoxyphenol. These phenolic compounds may
be used either singly or in any combination thereof.
In the present invention, at least one of these hydroxyl
group-containing organic compounds is used. The hydroxyl
group-containing organic compound is preferably an organic compound
having a boiling point of 100.degree. C. or higher and containing
one hydroxyl group. The boiling point of the hydroxyl
group-containing organic compound is preferably within a range of
100 to 290.degree. C. The hydroxyl group-containing organic
compound is preferably liquid at ordinary temperature (23.degree.
C.) from the viewpoint of handling. When the hydroxyl
group-containing organic compound is solid at ordinary temperature,
the melting point thereof is preferably 100.degree. C. or lower. If
the melting point of the hydroxyl group-containing organic compound
is too high, handling upon its introduction under pressure into the
polymerization reaction system becomes difficult, or a solvent is
required to convert it to a liquid state.
Among the hydroxyl group-containing organic compounds, aromatic
alcohols such as benzyl alcohol and phenolic compounds such as
phenoxyalcohol are preferred, and aromatic alcohols such as benzyl
alcohol are more preferred in that they are excellent in the effect
to reduce the bonded halogen atoms.
The hydroxyl group-containing organic compound is added into the
polymerization reaction system containing the organic amide solvent
and the formed polymer after the polymerization step. The
proportion of the hydroxyl group-containing organic compound added
is within a range of 0.001 to 20 mol, preferably 0.01 to 10 mol,
more preferably 0.05 to 5 mol per 100 mol of the charged sulfur
source.
After the hydroxyl group-containing organic compound is added into
the polymerization reaction system, the formed polymer is reacted
with the hydroxyl group-containing organic compound under
conditions of a temperature ranging generally from 170 to
290.degree. C., preferably from 200 to 280.degree. C., more
preferably from 245 to 270.degree. C. and a reaction time ranging
generally from 5 minutes to 3 hours, preferably from 30 minutes to
2 hours. A reaction product between the poly(arylene sulfide) and
the hydroxyl group-containing organic compound is formed by this
reaction, whereby at least part of bonded halogen atoms including
halogen atom(s) bonded to terminal(s) of its polymer chain are
removed. It may be presumed that a residue (for example, an ether
group) of the hydroxyl group-containing organic compound, which is
formed by the reaction of the hydroxyl group-containing organic
compound with the halogen atoms, is bonded to the reaction product.
In this reaction step, the molecular weight of the PAS formed may
also be more increased. The molecular weight of the PAS formed may
be lowered in the reaction step with the hydroxyl group-containing
organic compound in some cases according to the reaction conditions
in the polymerization step and the subsequent reaction step.
The production process according to the present invention
preferably comprises a phase-separation polymerization step of
creating a phase-separated state that a concentrated formed polymer
phase and a dilute formed polymer phase are present in a mixed
state within the polymerization reaction system in the presence of
the phase separation agent after the polymerization reaction of at
least one sulfur source selected from the group consisting of
alkali metal sulfides and alkali metal hydrosulfides with the
dihalo-aromatic compound is initiated in the polymerization step
and continuing the polymerization reaction in this phase-separated
state.
When the phase-separated state that the concentrated formed polymer
phase and the dilute formed polymer phase are present in a mixed
state within the polymerization reaction system (liquid phase) is
created in the presence of the phase separation agent, the
concentration of PAS in the concentrated phase is generally 30 to
70% by mass, preferably 40 to 60% by mass, more preferably 45 to
55% by mass. The concentration of PAS in the dilute phase is
generally 0 to 10% by mass, preferably 0 to 8% by mass, more
preferably 0 to 5% by mass. In the polymerization step, the
polymerization reaction is generally caused to proceed in a state
that the concentrated formed polymer phase has been dispersed as
droplets in the dilute formed polymer phase because the
polymerization reaction system (liquid phase) is stirred.
When the polymerization step comprises the phase-separation
polymerization step, it is preferable from the viewpoint of raising
the reaction efficiency that the hydroxyl group-containing organic
compound is added into the polymerization reaction system lying in
the phase-separated state after the phase-separation polymerization
step to cause the formed polymer to react with the hydroxyl
group-containing organic compound while retaining the
phase-separated state. When the hydroxyl group-containing organic
compound is added while retaining the state that the concentrated
formed polymer phase has been dispersed as droplets in the dilute
formed polymer phase under stirring, the hydroxyl group-containing
organic compound migrates to the concentrated formed polymer phase
and efficiently reacts with the formed polymer therein.
As preferred embodiments of the production process according to the
present invention, may be mentioned the following production
processes comprising a phase-separation polymerization step.
As a first production process, may be mentioned a production
process, in which the polymerization step comprises a
phase-separation polymerization step of continuing the
polymerization reaction in the presence of a phase separation agent
in a phase-separated state that a concentrated formed polymer phase
and a dilute formed polymer phase are present in a mixed state
within the polymerization reaction system after the polymerization
reaction of at least one sulfur source selected from the group
consisting of alkali metal sulfides and alkali metal hydrosulfides
with the dihalo-aromatic compound is initiated, the reaction step
is a step of adding the hydroxyl group-containing organic compound
into the polymerization reaction system lying in the
phase-separated state after the phase-separation polymerization
step to cause the formed polymer to react with the hydroxyl
group-containing organic compound while retaining the
phase-separated state, and the recovering step is a collecting step
of collecting a polymer formed in the reaction step from the
polymerization reaction system containing the formed polymer after
the reaction step.
As a second production process, may be mentioned a production
process, in which the polymerization step comprises: i) a
first-stage polymerization step of subjecting at least one sulfur
source selected from the group consisting of alkali metal sulfides
and alkali metal hydrosulfides and the dihalo-aromatic compound to
a polymerization reaction in the organic amide solvent to form a
polymer that a conversion of the dihalo-aromatic compound is 80 to
99%; and ii) a second-stage polymerization step of continuing the
polymerization reaction in the presence of the phase separation
agent in the phase-separated state that the concentrated formed
polymer phase and the dilute formed polymer phase are present in a
mixed state within the polymerization reaction system,
the reaction step is a step of adding the hydroxyl group-containing
organic compound into the polymerization reaction system lying in
the phase-separated state after the second-stage polymerization
step to cause the formed polymer to react with the hydroxyl
group-containing organic compound while retaining the
phase-separated state, and
the recovering step is a collecting step of collecting a polymer
formed in the reaction step from the polymerization reaction system
containing the formed polymer after the reaction step.
As a third production process, may be mentioned a production
process, in which the polymerization step comprises: I) a
first-stage polymerization step of subjecting at least one sulfur
source selected from the group consisting of alkali metal sulfides
and alkali metal hydrosulfides and the dihalo-aromatic compound to
a polymerization reaction at a temperature of 170 to 270.degree. C.
in the organic amide solvent in a state that water is present in a
proportion of generally 0.02 to 2.0 mol, preferably 0.05 to 2.0
mol, more preferably 0.5 to 2.0 mol per mol of the charged sulfur
source, thereby forming a polymer that a conversion of the
dihalo-aromatic compound is 80 to 99%; and II) a second-stage
polymerization step of controlling the amount of water in the
polymerization reaction system so as to bring about a state that
water exists in a proportion of from higher than 2.0 mol to not
higher than 10 mol per mol of the charged sulfur source, and
heating the polymerization reaction system to a temperature of 245
to 290.degree. C., thereby continuing the polymerization reaction
in the phase-separated state that the concentrated formed polymer
phase and the dilute formed polymer phase are present in a mixed
state within the polymerization reaction system,
the reaction step is a step of adding the hydroxyl group-containing
organic compound into the polymerization reaction system lying in
the phase-separated state after the second-stage polymerization
step to cause the formed polymer to react with the hydroxyl
group-containing organic compound while retaining the
phase-separated state, and
the recovering step is a collecting step of collecting a polymer
formed in the reaction step from the polymerization reaction system
containing the formed polymer after the reaction step.
In the second-stage polymerization step, water is preferably used
as the phase separation agent. However, another phase separation
agent (polymerization aid; for example, an organic carboxylic acid
metal salt) may be used in place of water or together with water
within a range of preferably 0.01 to 3 mol per mol of the charged
sulfur source.
As a fourth production process, may be mentioned a production
process comprising: 1) a dehydration step of heating a mixture
containing the organic amide solvent, a sulfur source containing an
alkali metal hydrosulfide, and an alkali metal hydroxide in a
proportion of 0.95 to 1.05 mol per mol of the alkali metal
hydrosulfide to discharge at least a part of a distillate
containing water from the interior of the system containing the
mixture to the exterior of the system; 2) a charging step of adding
an alkali metal hydroxide and water to the mixture remaining in the
system after the dehydration step, as needed, to adjust the mixture
in such a manner that the total number of moles of the number of
moles of an alkali metal hydroxide formed with hydrogen sulfide
formed upon the dehydration, the number of moles of the alkali
metal hydroxide added prior to the dehydration and the number of
moles of the alkali metal hydroxide added after the dehydration
becomes 1.00 to 1.09 mol, preferably more than 1.00 mol, but not
more than 1.09 mol per mol of a charged sulfur source existing in
the system after the dehydration step, and the number of moles of
water becomes generally 0.02 to 2.0 mol, preferably 0.05 to 2.0
mol, more preferably 0.5 to 2.0 mol per mol of the charged sulfur
source; 3) a first-stage polymerization step of adding the
dihalo-aromatic compound to the mixture to subject the sulfur
source and the dihalo-aromatic compound to a polymerization
reaction at a temperature of 170 to 270.degree. C. in the organic
amide solvent, thereby forming a polymer that a conversion of the
dihalo-aromatic compound is 80 to 99%; 4) a second-stage
polymerization step of controlling the amount of water in the
polymerization reaction system so as to bring about a state that
water exists in a proportion of from higher than 2.0 mol to not
higher than 10 mol per mol of the charged sulfur source, and
heating the polymerization reaction system to a temperature of 245
to 290.degree. C., thereby continuing the polymerization reaction
in the phase-separated state that the concentrated formed polymer
phase and the dilute formed polymer phase are present in a mixed
state within the polymerization reaction system; 5) a step of
adding the hydroxyl group-containing organic compound into the
polymerization reaction system lying in the phase-separated state
after the second-stage polymerization step to cause the formed
polymer to react with the hydroxyl group-containing organic
compound while retaining the phase-separated state; and 6) a
collecting step of collecting a polymer formed in the reaction step
from the polymerization reaction system containing the formed
polymer after the reaction step.
In the second-stage polymerization step, water is preferably used
as the phase separation agent. However, another phase separation
agent (polymerization aid; for example, an organic carboxylic acid
metal salt) may be used in place of water or together with water
within a range of preferably 0.01 to 3 mol per mol of the charged
sulfur source.
When water is used as the phase separation agent in the
polymerization step of the present invention, such a 2-stage
polymerization process as described above is preferably adopted.
The above-described second-stage polymerization steps are each a
phase-separation polymerization step. No phase-separated state
appears in the first-stage polymerization step. In the second-stage
polymerization step in which water has been added, the
polymerization reaction system (liquid phase) is phase-separated
into a concentrated polymer phase high in the content of the
polymer formed in the first-stage polymerization and a dilute
polymer phase low in the content of the polymer. The
phase-separated state can be visually clearly observed. Even when
water is used as the phase separation agent in the second-stage
polymerization step, another phase separation agent (polymerization
aid; for example, an organic carboxylic acid metal salt) may be
used within a range of preferably 0.01 to 3 mol per mol of the
charged sulfur source.
If the hydroxyl group-containing organic compound is added at an
initial stage of the polymerization reaction, for example, in the
charging step, the molecular weight (melt viscosity) of a PAS
formed is lowered to encounter difficulty on obtaining a
high-molecular weight PAS. If the hydroxyl group-containing organic
compound is added in a step (first-stage polymerization step) prior
to the phase-separation polymerization step, the molecular weight
(melt viscosity) of a PAS formed is also lowered. In the production
process according to the present invention, it is preferable to
adopt a process, in which the hydroxyl group-containing organic
compound is added into the polymerization reaction system lying the
phase-separated state after the second-stage polymerization step to
cause the formed polymer to react with the hydroxyl
group-containing organic compound while retaining the
phase-separated state because the terminal halogen atoms of the
formed polymer can be caused to efficiently react with the hydroxyl
group-containing organic compound. This phase-separated state means
a liquid-liquid phase-separated state. If the temperature within
the polymerization reaction system is too low, the formed polymer
comes to be solidified and precipitated. In such a solid-liquid
phase-separated state, the reaction efficiency between the hydroxyl
group-containing organic compound and the formed PAS is markedly
lowered.
11. Collecting Step
In the production process according to the present invention, a
post treatment after the reaction may be conducted in the same
manner as in the post treatment after an ordinary polymerization
reaction. For example, after completion of the reaction, a product
slurry cooled is separated by filtration as it is or after diluted
with water or the like, and the resulting filter cake is washed and
filtered repeatedly and then dried, whereby a PAS can be collected.
The washing is preferably conducted by a suitable combination of
water washing, washing with an organic solvent, acid washing, etc.
until a secondarily formed alkali metal salt and oligomers are
removed.
According to the production process comprising the phase-separation
polymerization step, a granular PAS can be formed, so that a method
of separating the granular PAS from the reaction mixture by a
method of sieving the polymer by means of a screen is preferably
adopted because the polymer can be easily separated from
by-products, oligomers, etc. The product slurry may be subjected to
sieving in a high-temperature state, thereby collecting the
polymer.
After the separation by filtration, the PAS is preferably washed
with the same organic amide solvent as the polymerization solvent,
or an organic solvent such as a ketone (for example, acetone) or an
alcohol (for example, methanol). The PAS may be washed with hot
water or the like. The formed PAS may also be treated with an acid
or a salt such as ammonium chloride.
12. Poly(Arylene Sulfide)
According to the production process of the present invention, a PAS
whose content (also referred to as "halogen content" merely) of
bonded halogen atoms mainly composed of terminal halogen groups has
been reduced can be produced. The content of the bonded halogen
atoms is generally lower than 4,000 ppm, preferably 3,900 ppm or
lower, more preferably 3,800 ppm or lower. In many cases, the
content of the bonded halogen atoms can be reduced to 2,000 ppm or
lower, further to 1,500 ppm or lower. The lower limit of the
content of the bonded halogen atoms is generally 50 ppm, often 100
ppm or 200 ppm.
In order to further reduce the content of the bonded halogen atoms
in the PAS, for example, the treatment method for PAS disclosed in
Patent Literature 2 may be added. However, a large amount of a
filler is added when the PAS according to the present invention is
used as a sealing compound for electronic parts, so that the PAS
can be practically used without causing inconvenience even when the
content of the bonded halogen atoms falls within the above range,
and the PAS can satisfy the level of requirements of halogen
content reduction in products from various fields. The PAS
according to the present invention can be used as a sealing
compound for electronic parts as a compound containing a large
amount of a filler. The PPS content in the compound is lowered by
adding the filler, so that the content of the bonded halogen atoms
is also lowered to about 50 to 60% by mass. When the content of the
bonded halogen atoms in the compound is 800 to 900 ppm or lower,
such a PAS can meet, for example, the regulation value in Europe
and the requirement value by the industries associated with
electronic parts. Therefore, the content of the bonded halogen
atoms in the PAS is particularly desirably 1,500 ppm or lower.
The content of the bonded halogen atoms can be reduced to 2,000 ppm
or lower, further to 1,500 ppm or lower without lowering the
average particle diameter, yield, etc. by, for example, controlling
the amount of the dihalo-aromatic compound charged within a range
of from more than 1.00 mol to less than 1.06 mol, preferably 1.01
to 1.05 mol per mol of the sulfur source (alkali metal sulfide
and/or alkali metal hydrosulfide) remaining in the system after the
dehydration step and using an aromatic alcohol such as benzyl
alcohol as the hydroxyl group-containing organic compound in the
production process according to the present invention as shown in
Example 1 which will be described subsequently.
The content of the bonded halogen atoms can be reduced to 1,500 ppm
or lower, further to 1,000 ppm or lower by, for example,
controlling the amount of the dihalo-aromatic compound charged
within a range of 1.06 to 1.09 mol per mol of the sulfur source
(alkali metal sulfide and/or alkali metal hydrosulfide) remaining
in the system after the dehydration step and using an aromatic
alcohol such as benzyl alcohol as the hydroxyl group-containing
organic compound in the production process according to the present
invention as shown in Example 2 which will be described
subsequently. In this case, the resultant PAS shows a tendency to
low its melt viscosity. However, a filler can thereby be filled in
a high proportion therein, so that the PAS can be suitably applied
to uses such as a sealing compound.
According to the production process of the present invention, a PAS
having a melt viscosity of generally 1 to 100 Pas, preferably 2 to
80 Pas, particularly preferably 3 to 70 Pas as measured at a
temperature of 310.degree. C. and a shear rate of 1,216 sec.sup.-1
can be obtained. According to the production process of the present
invention, a PAS having a weight-average molecular weight of
generally 10,000 to 60,000, preferably 13,000 to 55,000,
particularly preferably 14,000 to 50,000 can be obtained.
According to the production process of the present invention, a
granular polymer captured on a screen having a sieve opening size
of 150 p.m (100 mesh) can be collected at a yield of generally 80
to 98%, preferably 83 to 97%, particularly preferably 85 to 95%.
According to the production process of the present invention, a
granular PAS having an average particle diameter of 100 to 1,000
.mu.m, preferably 150 to 800 .mu.m, more preferably 200 to 500
.mu.m can be obtained.
When the above-described features are summarized, according to the
production process of the present invention, there can be provided
a poly(arylene sulfide) obtained by subjecting at least one sulfur
source selected from the group consisting of alkali metal sulfides
and alkali metal hydrosulfides and the dihalo-aromatic compound to
a polymerization reaction in the organic amide solvent, wherein (a)
at least part of halogen atoms bonded to terminals of its polymer
chain have been removed by a reaction with the hydroxyl
group-containing organic compound, (b) the melt viscosity thereof
is 1 to 100 Pas as measured at a temperature of 310.degree. C. and
a shear rate of 1,216 sec.sup.-1, (c) the weight-average molecular
weight thereof is 10,000 to 60,000 as measured by gel permeation
chromatography, (d) the average particle diameter thereof is 100 to
1,000 .mu.m as measured by a sifting method, and (e) the content of
bonded halogen atoms thereof is lower than 4,000 ppm as measured by
the flask combustion method.
The PAS obtained by the production process according to the present
invention can be molded or formed into various injection-molded
products (including sealed molded products by injection) or
extruded products such as sheets, films, fibers and pipes either
singly or by incorporating various kinds of inorganic fillers,
fibrous fillers and/or various kinds of synthetic resins as it is
or after subjected to oxidative crosslinking. The PAS may also be
used as a covering material. The PAS is particularly preferably
PPS.
EXAMPLES
The present invention will hereinafter be described more
specifically by the following Examples and Comparative Example.
However, the present invention is not limited to these examples
alone. Measuring methods of physical properties and properties or
characteristics in the present invention are as follows.
(1) Yield
After a reaction, the reaction mixture was sifted through a
plurality of screens different in sieve opening size and then
fractionated and washed. A polymer captured on a screen having a
sieve opening size of 150 .mu.m (100 mesh) was regarded as "a
granular polymer". Assuming that all the available sulfur component
in a charged sulfur source existing in a reaction vessel after a
dehydration step was converted to a polymer, the yield of the
granular polymer was based on the mass (theoretical amount) of that
polymer. When the charged sulfur source is charged in excess in
terms of a molar ratio to the dihalo-aromatic compound, all the
charged sulfur source may not be converted to a polymer in some
cases. Even in that case, the yield is calculated out on the basis
of the amount of the charged sulfur source for the present.
(2) Average Particle Diameter
The average particle diameter of a polymer collected was measured
by a sifting method using sieves of mesh #7 (sieve opening size:
2,800 .mu.m), mesh #12 (sieve opening size: 1,410 .mu.m), mesh #16
(sieve opening size: 1,000 .mu.m), mesh #24 (sieve opening size:
710 .mu.m), mesh #32 (sieve opening size: 500 .mu.m), mesh #60
(sieve opening size: 250 .mu.m), mesh #100 (sieve opening size: 150
.mu.m), mesh #145 (sieve opening size: 105 .mu.m) and mesh #200
(sieve opening size: 75 .mu.m) as sieves used.
(3) Content of Bonded Halogen Atom
A polymer sample, from which all of secondarily produced alkali
metal salts had been substantially removed by washing, was used to
measure a content of a halogen (chlorine) atom by the flask
combustion method.
(4) Weight-Average Molecular Weight
The weight-average molecular weight (Mw) of a polymer was measured
under the following conditions by using a high-temperature gel
permeation chromatograph (GPC) SSC-7000 manufactured by Senshu
Scientific Co., Ltd. The weight-average molecular weight was
calculated out as a value converted from polystyrene. Solvent:
1-chloronaphthalene, Temperature: 210.degree. C., Detector: UV
detector (360 nm), Amount of sample injected: 200 .mu.l
(concentration: 0.05% by mass), Flow rate: 0.7 ml/min, and Standard
polystyrene: 5 standard polystyrenes of 616,000, 113,000, 26,000,
8,200 and 600. (5) Melt Viscosity
A melt viscosity was measured by using about 20 g of a dry granular
polymer by means of Capirograph 1-C (trademark) manufactured by
Toyo Seiki Seisakusho, Ltd.). A flat die with a capillary of 1 mm
in diameter.times.10 mm in length was used, and the temperature was
set to 310.degree. C. After the polymer sample was introduced into
the apparatus and held for 5 minutes, the melt viscosity was
measured at a shear rate of 1,216 sec.sup.-1.
Comparative Example 1
A 20-liter autoclave was charged with 5,999 g of
N-methyl-2-pyrrolidone (hereinafter abbreviated as "NMP"), 2,000 g
of sodium hydrosulfide (NaSH; purity: 62% by mass, containing 15 g
of Na.sub.2S) and 1,192 g of sodium hydroxide (NaOH; purity: 73.5%
by mass). A molar ratio of sodium hydroxide/sulfur source (NaOH/S)
was 0.978, and a molar ratio of NaOH/NaSH was 0.990. These sodium
hydrosulfide and sodium hydroxide of the respective purities
contain water such as water of hydration as a remaining
component.
After the interior of the autoclave was purged with nitrogen gas,
the contents were gradually heated to 200.degree. C. over about 4
hours with stirring to distill off 997 g of water (H.sub.2O), 1,244
g of NMP and 12 g of hydrogen sulfide (H.sub.2S).
After the dehydration step, the contents in the autoclave were
cooled to 150.degree. C., and 3,416 g of p-dichlorobenzene
(hereinafter abbreviated as "pDCB"), 3,464 g of NMP, 40 g of sodium
hydroxide (high-purity product) and 145 g of water were added. A
ratio (NMP/charged S; g/mol) of NMP/charged sulfur source
(hereinafter abbreviated as "charged S") in the autoclave was 375,
a ratio (mol/mol) of pDCB/charged S was 1.06, a ratio (mollmol) of
H.sub.2O/charged S was 1.50, and a ratio (mollmol) of Na0Hlcharged
S was 1.07.
While stirring the contents in the autoclave at 250 rpm by a
stirrer, a reaction was conducted at 220.degree. C. for 3 hours to
conduct first-stage polymerization. A conversion into a polymer by
the first-stage polymerization was 93%. The number of revolutions
of the stirrer was then increased to 400 rpm, and 454 g of water
was charged under pressure while continuing the stirring. A ratio
(mollmol) of H.sub.2O/charged S was 2.65. The contents in the
autoclave were heated to 255.degree. C. and reacted for 4 hours to
conduct second-stage polymerization.
After completion of the second-stage polymerization, the contents
were cooled near to room temperature and then sifted through a
100-mesh screen to collect a granular polymer. The granular polymer
was washed 3 times with acetone, 3 times with water, once with an
aqueous solution of acetic acid adjusted to a pH of 4 and then
additionally 4 times with water to obtain a washed granular
polymer. The granular polymer was dried for 24 hours at a
temperature of 100.degree. C. in a thermostatic chamber. The yield
of the granular polymer thus obtained was 88%, and the polymer had
an average particle diameter of 350 .mu.m, a melt viscosity of 30
Pas, a weight-average molecular weight Mw of 46,000 and a chlorine
content of 4,000 ppm. The results are shown in Table 1.
Example 1
A 20-liter autoclave was charged with 6,002 g of
N-methyl-2-pyrrolidone (NMP), 2,000 g of sodium hydrosulfide (NaSH;
purity: 62% by mass, containing 25 g of Na.sub.2S) and 1,188 g of
sodium hydroxide (NaOH; purity: 73.5% by mass). A molar ratio of
sodium hydroxide/sulfur source (NaOH/S) was 0.967, and a molar
ratio of NaOH/NaSH was 0.987.
After the interior of the autoclave was purged with nitrogen gas,
the contents were gradually heated to 200.degree. C. over about 4
hours with stirring to distill off 983 g of water (H.sub.2O), 1,019
g of NMP and 13 g of hydrogen sulfide (H.sub.2S).
After the dehydration step, the contents in the autoclave were
cooled to 150.degree. C., and 3,287 g of p-dichlorobenzene (pDCB),
3,197 g of NMP, 9 g of sodium hydroxide (high-purity product) and
133 g of water were added. A ratio (NMP/charged S; g/mol) of
NMP/charged sulfur source (charged S) in the autoclave was 375, a
ratio (mollmol) of pDCB/charged S was 1.025, a ratio (mol/mol) of
H.sub.2O/charged S was 1.50, and a ratio (mol/mol) of NaOH/charged
S was 1.05.
While stirring the contents in the autoclave at 250 rpm by a
stirrer, a reaction was conducted at 220.degree. C. for 3 hours to
conduct first-stage polymerization. A conversion into a polymer by
the first-stage polymerization was 94%. The number of revolutions
of the stirrer was then increased to 400 rpm, and 452 g of water
was charged under pressure while continuing the stirring. A ratio
(mol/mol) of H.sub.2O/charged S was 2.65. The contents in the
autoclave were heated to 255.degree. C. and reacted for 4 hours to
conduct second-stage polymerization. After completion of the
second-stage polymerization, benzyl alcohol was charged under
pressure in a proportion of 0.1 mol per 100 mol of the charged
sulfur source by a pump to conduct a reaction for additionally 1
hour.
After the reaction system was cooled near to room temperature, the
contents were treated under the same conditions as in Comparative
Example 1. The yield of the granular polymer thus obtained was 92%,
and the polymer had an average particle diameter of 400 tun, a melt
viscosity of 31 Pas, a weight-average molecular weight Mw of 48,000
and a chlorine content of 1,200 ppm. The results are shown in Table
1.
Example 2
First-stage polymerization and second-stage polymerization were
conducted under the same conditions as in Comparative Example 1.
After completion of the second-stage polymerization, benzyl alcohol
was charged under pressure in a proportion of 0.1 mol per 100 mol
of the charged sulfur source by a pump to conduct a reaction for
additionally 1 hour. After the reaction system was cooled near to
room temperature, the contents were treated under the same
conditions as in Comparative Example 1. The yield of the granular
polymer thus obtained was 87%, and the polymer had an average
particle diameter of 250 .mu.m, a melt viscosity of 5 Pas, a
weight-average molecular weight Mw of 18,000 and a chlorine content
of 800 ppm. The results are shown in Table 1.
Example 3
First-stage polymerization and second-stage polymerization were
conducted under the same conditions as in Comparative Example 1.
After completion of the second-stage polymerization, phenoxyphenol
was charged under pressure in a proportion of 0.1 mol per 100 mol
of the charged sulfur source by a pump to conduct a reaction for
additionally 1 hour. After the reaction system was cooled near to
room temperature, the contents were treated under the same
conditions as in Comparative Example 1. The yield of the granular
polymer thus obtained was 90%, and the polymer had an average
particle diameter of 350 .mu.m, a melt viscosity of 22 Pas, a
weight-average molecular weight Mw of 33,000 and a chlorine content
of 3,700 ppm. The results are shown in Table 1.
TABLE-US-00001 TABLE 1 Hydroxyl group-containing organic compound
Organic Polymer pDCB/charged compound/ Particle sulfur source
charged S Cl content M.V. Yield diameter mol/mol Kind mol/mol Time
added ppm Pa s Mw % .mu.m Example 1 1.025/1 Benzyl 0.1/100 After
second-stage 1,200 31 48,000 92 400 alcohol polymerization Example
2 1.06/1 Benzyl 0.1/100 After second-stage 800 5 18,000 87 250
alcohol polymerization Example 3 1.06/1 Phenoxy- 0.1/100 After
second-stage 3,700 22 33,000 90 350 phenol polymerization
Comparative 1.06/1 -- -- -- 4,000 30 46,000 88 350 Example 1
INDUSTRIAL APPLICABILITY
The poly(arylene sulfides) obtained by the production process
according to the present invention can be molded or formed into
various injection-molded products or extruded products such as
sheets, films, fibers and pipes either singly or by incorporating
various kinds of inorganic fillers, fibrous fillers and/or various
kinds of synthetic resins as it is or after subjected to oxidative
crosslinking. The poly(arylene sulfides) according to the present
invention can be particularly suitably utilized in a wide variety
of fields such as electrical and electronic equipments and
automotive equipments, including sealing compounds for electronic
parts.
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